Mass flow multiplier refrigeration cycle

ABSTRACT

The ejector mass flow multiplier refrigeration cycle utilizes a single-phase ejector which is operated at a high entrainment ratio and performs the function as a mass flow multiplier. The high-pressure motive force input into the single-phase ejector is provided by a vapor compressor which sucks a portion of the output mass flow from an evaporator with the remaining mass flow output from the evaporator being sucked into low-pressure port of the same single-phase ejector. The low-pressure output of the single-phase ejector is inputted into the low-pressure port of a two-phase ejector where the mass flow pressure is increased for the temperature conditions of a condenser. A high-pressure liquid pump provides the motive force input of the two-phase ejector and for the input to an evaporator where the cooling effect of the system takes place.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a refrigeration system, which utilizes an evaporator(s), condenser, vapor compressor, single-phase ejector, two-phase ejector and a liquid pressure pump.

2. Description of the Prior Art

The vapor compression refrigeration cycle is the predominate cooling method for millions of residential and commercial installations. The vapor compression cycle utilizes a vapor compressor to increase a low-pressure refrigerant gas to a high-pressure refrigerant gas. The high-pressure gas then passes through an air or water-cooled condenser where the gas changes state into a high-pressure, liquid upon the removal of heat from the high-pressure gas. This high-pressure liquid then passes through an expansion valve into an evaporator. During this expansion process, heat is absorbed in the evaporator with space air or other medium being circulated through the evaporator. The net result is the cooling of the conditioned space or medium.

A further improvement to the above vapor compression refrigeration cycle is a vapor-compression refrigeration cycle with ejector as shown in FIG. 1. This ejector cycle described in U.S. Pat. No. 6,438,993, reduces the amount of work or energy input required by the vapor compressor. High-pressure refrigerant is decompressed and expanded in a nozzle of an ejector with the liquid-phase refrigerant separated in a gas-liquid separator is supplied to an evaporator by the pumping function of the ejector. Further, in the above ejector cycle, a pressure of refrigerant to be sucked into a compressor is increased by converting expansion energy to Pressure energy, so that consumption power of the vapor compressor is reduced.

SUMMARY

The present invention consists of a vapor compressor which is rated at a fraction of the overall system cooling capability. The vapor compressor at its rated flow capacity sucks a portion of the low-pressure gas output from an evaporator and compresses the vapor into a high pressure gas which provides the primary motive force input flow into a single-phase ejector. Concurrently, the remaining low pressure volume output from the evaporator passes into the low-pressure input port of the same single-phase ejector. The purpose of this single-phase ejector is not to increase the pressure output but to produce a high entrainment or sucking ratio (ER) which performs as a system mass flow multiplier. Reference is made to “A Dissertation by Chaqing Liao” entitled “GAS EJECTOR MODELING FOR DESIGN AND ANALYSIS”, Office of Graduate Studies of Texas A&M University. This document outlines the design parameters for a single-phase ejector with a high ER.

The output of the above single-phase ejector is inputted into the low pressure input port of a two-phase ejector whose purpose is to increase the output pressure necessary for the temperature conditions of the condenser. The motive force input into the two-phase ejector is provided by a high-pressure liquid pump. The pressure enhancement capabilities of a typical two-phase ejector are more fully described in an early U.S. Pat. No. 3,277,660 and most recently refined in U.S. Pat. No. 6,438,993. The high-pressure vapor output of the two-phase ejector is inputted into a condenser where a phase change into a high-pressure liquid pressure is accomplished.

The high-pressure liquid from the condenser proceeds into a high-pressure liquid pump where the liquid pressure is further increased. Upon leaving the liquid pressure pump, the output is divided into two liquid streams. The first stream is directed into the driving motive force input port of the two-phase ejector, while the second stream is directed into the expansion valve then into the evaporator. During this expansion process, heat is absorbed in the evaporator with space air or other medium being circulated through the evaporator. The net result is the cooling of the conditioned space or medium.

The net refrigeration output of this cycle is a function of the mass flow of the vapor compressor plus the ER of the single-phase ejector times the mass flow of the vapor compressor.

It is an object of the invention to provide a simple refrigeration system with significant advantages over the vapor compressor system widely in use today.

Additional objects and advantages of the invention are set forth, in part in the description which follows, and in part, will be obvious from description or may learned by practice of the invention. The objects and advantages of the invention will be realized in detail by means of the instrumentalities and combinations particularly pointed out in the appended claim.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional objects and advantages of the invention will be more readily apparent from the following detailed description of the preferred embodiment, when taken together with the accompanying drawings, in which:

FIG. 1 is a schematic diagram showing an ejector cycle (vapor-compression refrigerant cycle) according to U.S. Pat. No. 6,438,993;

FIG. 2 is a schematic diagram showing a mass flow multiplier refrigeration cycle used in the present invention;

FIG. 3 is a schematic diagram showing a mass flow multiplier refrigeration cycle with the addition of a second evaporator.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

It is understood that both the foregoing general description and following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed. The accompanying drawings as shown in FIG. 2 and FIG. 3 which are incorporated herein for reference, and constitute part of the specifications, illustrate certain embodiments of the invention, and together with the detailed description serve to explain the principles of the present invention.

As shown in FIG. 2 the refrigeration cycle of the present invention utilizes a typical refrigerant such as R134a and begins with a portion of the low pressure vapor output from evaporator 23 proceeding through conduits 24 and 25 and is sucked into the vapor compressor 10 where the vapor is increased from a low to a high-pressure output.

This high-pressure vapor refrigerant proceeds through conduit 11 into the driving motive force input port 12 a of a single-phase ejector 12 (ejector 12). The motive force flow is accelerated to supersonic speed by a converging-diverging nozzle. The primary flow exit in the ejector suction chamber induces a secondary flow by this high-velocity depressurized flow. Concurrently the remaining portion of the low-pressure gas output from evaporator 23 proceeds through conduits 24 and 26 into the low pressure port 12 b of ejector 12. This is accomplished by the sucking or entrainment capabilities of ejector 12. The ejector 12 operating parameters are set such that the entrainment ratio (ER) is maximized. This requires that the output at port 12 c works against a low back pressure.

The low-pressure output from port 12 c of ejector 12 is directed into the low-pressure suction port of a two-phase ejector 14 (ejector 14) via conduit 13. Concurrently a high-pressure liquid stream from a high-pressure liquid pump 17 flows through conduits 16 and 15 into the driving motive force input port 14 a of ejector 14. It is to be noted that the horsepower to pressurize a liquid for a given mass flow of refrigerant by a positive displacement pressure pump is significantly less than the horsepower required for a vapor compression cycle of equal mass flow. The input into port 14 a of ejector 14 decompresses and mixes with the low-pressure gas output from ejector 12. The ejector 14 performs two functions, the first being the entrainment or sucking of low-pressure vapor from ejector 12 into the low-pressure input port 14 b. The second function is the conversion of speed energy into pressure energy enhancement which is required for the temperature conditions of condenser 19.

The pressure enhancement capabilities of a typical two-phase ejector are more fully described in an early U.S. Pat. No. 3,277,660 and most recently described in U.S. Pat. No. 6,438,993. Upon leaving port 14 c of ejector 14, the refrigerant travels through conduit 20 and enters condenser 19 where heat is removed thereby condensing the refrigerant into a high-pressure liquid. This high-pressure liquid proceeds through conduit 18 into a high-pressure liquid pump 17 where the liquid pressure is further increased. Upon leaving the liquid pressure pump 17, the high-pressure liquid passes through conduit 16 where the flow is divided into two liquid streams. The first stream is directed through conduit 15 into the driving motive force input port 14 a of ejector 14, while the second stream is directed through conduit 21 entering the expansion valve 22 then into evaporator 23. The expansion valve 22 opens and closes depending upon the set point temperature requirements of the evaporator 23. There are several schemes to accomplish this control function currently in use today. During this expansion process the refrigerant undergoes a phase change whereby heat is absorbed in the evaporator 23 with space air or other medium being circulated through evaporators 23. The net result is the cooling of the conditioned space or medium.

Again a portion of the low-pressure output of evaporator 23 travels through conduits 24 and 25 into the vapor compressor 10. Concurrently, the remaining output of evaporator 23 travels through conduits 24 and 26 into the low-pressure port 12 b of the ejector 12. This final step completes the cycle where it is then repeated.

It is to be noted that an alternate variation to the above cycle is shown in FIG. 3 where a second evaporator 23A is added. Beginning with conduit 21 the liquid stream is divided whereby the majority of the mass flow proceeds through conduit 21A into expansion valve 22A then into evaporator 23A. The low-pressure output from evaporator 23A proceeds through conduits 26A and 26 into the low-pressure input port 12 b of ejector 12.

It will be apparent to those skilled in the art that various modifications can be made in the construction and configuration of the present invention without departing from the scope or spirit of the invention. For example, the embodiment mentioned above is illustrative and explanatory only. Various changes can be made in material as well as the configuration of the device to engineer the specific desired outcome. Thus it is intended that the present invention cover the modifications and variations of the invention, provided they come within the scope of the appended claims and their equivalents. 

What is claimed is:
 1. A mass flow multiplier refrigeration cycle comprising: a vapor compressor for sucking and converting a low-pressure vapor refrigerant into a high-pressure vapor refrigerant. The vapor compressor capacity is a fraction of the overall system refrigeration output; an evaporator(s) for evaporating a low-pressure refrigerant after being decompressed in which heat is absorbed; an expansion valve(s) for decompressing a high-pressure liquid refrigerant into a low-pressure refrigerant for input into an evaporator; a condenser for converting a high-pressure vapor refrigerant into a high-pressure liquid refrigerant by the removal of heat; a high pressure liquid pump which increases the liquid refrigerant into a higher pressure whose mass flow is a multiple of the systems rated capability; a single-phase ejector whose operating parameters are such that the ER (entrainment ratio) is maximized; a two-phase ejector whose operating parameters are such that the output pressure is increased for the temperature conditions of a condenser. 